Permanent fitting for fluid-tight connections

ABSTRACT

A pipe connector has a coupling with a first cylindrical land, a second cylindrical land, and a third cylindrical land. There is a first annular recess defined between the first cylindrical land and the second cylindrical land, and a second annular recess defined between the second cylindrical land and the third cylindrical land. A gate channel communicates between the two recesses through the second cylindrical land. Circumferential seals extend around the first and third cylindrical lands. A cement injection port communicates between the outside of the connector and the first recess, and a cement vent port communicates between the outside of the connector and the second recess. In use, a pipe is inserted into the coupling to rest upon the three lands, and cement is forced into the injection port. The cement flows circumferentially around the first annular recess, through the gate opening, circumferentially around the second annular recess, and out through the vent port. The seals prevent the cement from flowing out of the interior of the connector.

BACKGROUND OF THE INVENTION

This invention relates to pipe fittings which are bound to pipe with apermanent cement, and, more particularly, to such fittings wherein thecement is injected into the fitting.

Pipes are assembled into fluid-conduction systems with fittings. In anapproach commonly used in home interior plumbing and outdoor irrigationsystems, plastic pipes are joined with plastic fittings. To build thefluid-conduction system, the pipes are normally cut to length, and thenthe pipe segments and fittings are "dry fitted" together without anypermanent cement present to be certain that the lengths andconfigurations are correct. The joints are thereafter seriallydisassembled, cement is applied to the joint of each fitting/pipe pair(optionally with a primer applied prior to the cement, where required)and the fitting and pipe are permanently reassembled by forcing the pipeinto the fitting. This latter sequence of steps is often termed "solventwelding".

This approach, while widely used, as some disadvantages. When thepermanent joining is made, an excess of cement is normally used. Theexcess is extruded out of the ends of the fitting or into its interior.Upon hardening, the cement may block a significant portion of theinterior cross-sectional area of the pipe, particularly where the pipeis of small diameter. The permanent assembly is desirably made with atwisting motion between the pipe and the fitting in an attempt to ensuregood circumferential contact of the cement to the pipe and the interiorof the fitting, but that twisting motion may not be possible for some ofthe joints. The cement often is made with a chemistry designed to setquickly, so that the reassembly must be made very quickly, whichsometimes leads to errors. Even when the reassembly is made properly,local dry spots in the cement joint may occur. The dry spots are theprincipal cause of leaks in such joints. Moreover, if a mistake is madein the dry fitting or during wet assembly and not discovered until afterthe solvent welding is completed, a portion of the fluid-conductionsystem must be cut out and replaced. In tight spots, the permanentassembly of the last portions of the fluid-conduction system after theearlier portions have been permanently assembled can be difficult due tospace constraints. Lastly, the solvent in the cement is evolved duringthe painting of cement onto the parts and from any exposed cement duringthe drying of the cement, which can be injurious to the user.

To overcome these problems, there have been proposed injection fittingswherein the fittings and the pipes are assembled and then the cement isinjected between the fitting and the pipe to make the assemblypermanent. The existing injection fitting structures and techniques havenot been fully satisfactory due to incomplete coverage of the cementover the internal surface of the joint, which can lead to weakness andleaking at the joint, and messiness due to leaking cement. The priorcement-injection fitting approaches have also not taken the irregularnature of the piping material into account. Most plastic pipe is formedby extrusion, and as a result in many cases the pipe is somewhatnon-cylindrical and of non-uniform diameter. The previously knownfittings for use in cement-injection techniques have been suitable underthe assumption that the plastic pipe was uniform, but have been moredifficult or impossible to use where non-uniform pipe, of the type foundin commerce, was utilized.

There is a need for an improved fitting and approach for use in thepermanent joining of pipe segments. The present invention fulfills thisneed, and further provides related advantages.

SUMMARY OF THE INVENTION

The present invention provides a coupling and fitting structure formaking connections to pipe and in other applications. The approachproduces a mechanically strong joint that is leak free, even when thepipe to be connected is somewhat irregular. The coupling structure isreadily manufactured in a variety of configurations. Using thisapproach, piping arrays are assembled quickly and conveniently in atrial arrangement and then permanently solvent bonded withouttime-consuming disassembly and its associated opportunities for error,and without exposing the user to significant amounts of volatile solventvapors.

In accordance with the invention, a connector structure to be used witha pipe of a pipe nominal diameter comprises a hollow body having anexternal surface and including at least a first coupling. The firstcoupling includes a first cylindrical internal land, a secondcylindrical internal land, and a third cylindrical internal land. Thefirst cylindrical land, the second cylindrical land, and the thirdcylindrical land are collinear and of a diameter sufficiently largerthan the pipe nominal diameter to permit the pipe to be slipped into thehollow body to rest upon the lands. There is a circumferentiallyextending internal first recess lying between the first cylindrical landand the second cylindrical land, a circumferentially extending internalsecond recess lying between the second cylindrical land and the thirdcylindrical land, and a gate channel through the second cylindrical landcommunicating between the first recess and the second recess at a gatechannel circumferential location. An injection port communicates betweenthe first recess and the external surface at a port circumferentiallocation which is remote from the gate channel circumferential location,and which is preferably displaced by about 180 degrees around thecircumference of the body from the gate channel circumferentiallocation. A vent port communicates between the second recess and theexternal surface at about the same circumferential position as the portcircumferential location. The vent port preferably has a smallercross-sectional area than the injection port to ensure a positivepressure within the recesses during injection of cement. Additionalcouplings of the same design can be provided to form straight fittings,elbow fittings, T-fittings, integral fittings, and other types offittings as may be desired.

Preferably, seals are provided at the ends of the coupling on the firstand third lands. These seals prevent cement from being forced out of theannular regions defined by the recesses during injection of cement. Theseals may be of any operable type, including an O-ring seal, anintegrally molded compliant seal, or a flap seal of the same materialused in the body of the structure.

In use, the pipe is inserted into the coupling to rest on the threelands. A stop is preferably provided at the end of the coupling todefine the proper position for the pipe. Without any disassembly, cementis injected into the injection port to flow around the circumference ofthe pipe in the first recess, through the gate channel, around thecircumference of the pipe in the second recess, and out the vent port.When cement emerges from the vent port, the filling is complete. Thesmall amount of exposed cement emits only a small fraction of thesolvent vapors produced by the conventional approach used to solventweld pipes. The cement is allowed to harden to complete the solventbonding, while other joints are filled.

More generally, a connector structure comprises a hollow body having anexternal surface and including at least a first coupling. The firstcoupling includes a first internal land, a second internal land, and athird internal land, wherein the first land, second land, and third landare collinear and congruent. A circumferentially extending internalfirst recess lies between the first land and the second land, acircumferentially extending internal second recess lies between thesecond land and the third land, and a gate channel through the secondland communicates between the first recess and the second recess at agate channel circumferential location. An injection port communicatesbetween the first recess and the external surface at a portcircumferential location. The port circumferential location is displacedby about 180 degrees around the circumference of the body from the gatechannel circumferential location. A vent port communicates between thesecond recess and the external surface at about the port circumferentiallocation.

The present approach thus provides a fitting and an approach for itsuse. Other features and advantages of the present invention will beapparent from the following more detailed description of the preferredembodiment, taken in conjunction with the accompanying drawings, whichillustrate, by way of example, the principles of the invention. Thescope of the invention is not, however, limited to this preferredembodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fitting having a coupling, with apiece of pipe inserted into the coupling;

FIG. 2A is a sectional view of the fitting of FIG. 1, taken along lines2--2;

FIG. 2B is an enlarged sectional view of a secondary embodiment of thefirst land and stop;

FIG. 2C is an enlarged sectional view of a secondary embodiment of thesecond land;

FIG. 3 is a sectional view of the fitting of FIG. 1, taken along lines3--3 of FIG. 2A;

FIG. 4 is a schematic perspective cutaway view of the fitting of FIG. 1,illustrating the liquid cement flow paths;

FIG. 5 is an enlarged detail of a first embodiment of the secondcircumferential seal of the fitting of FIG. 1, taken in the region 5--5of FIG. 2A;

FIG. 6 is an enlarged detail of a second embodiment of secondcircumferential seal of the fitting of FIG. 1, taken in the region 5--5of FIG. 2A;

FIG. 7 is an enlarged detail of a third embodiment of the secondcircumferential seal of the fitting of FIG. 1, taken in the region 5--5of FIG. 2A;

FIG. 8 is a schematic cross-sectional depiction of the configuration oftypical piping;

FIG. 9 is an elevational view of a portion of the fluid conductionsystem utilizing the approach of the invention;

FIG. 10 is a perspective view of a non-cylindrical hermetically sealedassembly; and

FIG. 11 is a block diagram of the preferred approach for utilizing thefittings of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a fitting 20 having at least one coupling 22, and inthis case two couplings 22, one at each end of the linear fitting 20.One end of a length of pipe 24 is inserted into one of the couplings 22,with the remainder of the length of pipe 24 protruding from the coupling22.

FIG. 2A is a sectional view of the fitting 20 and the two couplings 22.The length of pipe 24 inserted into the rightmost coupling 22 is shownin dashed lines. The coupling 22 is formed as a hollow body 26 which isgenerally cylindrical and has a cylindrical axis 28, although featuresdescribed herein preclude perfect cylindrical symmetry. The body has anexternal surface 30, which is generally cylindrical and an internalsurface 32 which also is generally cylindrical but which has a number offeatures thereon.

The internal surface 32 includes a first cylindrical internal land 34extending around the circumference of the internal surface 32. As usedherein, a "land" is a raised region adjacent to a recess in a surface.In some cases, the land lies between two recesses, while in other casesthe land lies adjacent to only one recess. The internal surface 32further includes a second cylindrical internal land 36 spaced apart fromthe first cylindrical internal land 34 along the axis 28 and a thirdcylindrical internal land 38 spaced apart from the second cylindricalinternal land 36 along the axis 28. The first cylindrical internal land34, the second cylindrical internal land 36, and the third cylindricalinternal land 38 of any one coupling 22 are collinear and of acylindrical diameter sufficiently large to admit the end of the pipe 24therein such that the pipe 24 rests upon the lands 34, 36, and 38 wheninserted into the coupling 22. Desirably, a stop 40 extending toward theaxis 28 is provided on the first land 34 to establish the proper extentto which the end of the pipe 24 may be inserted into the coupling 22.When the pipe 24 is inserted into the coupling 22, the end of the pipeengages the stop 40 to limit the degree of insertion.

The first land 34 may be flat as shown in FIG. 2A, or tapered inwardlywith increasing distance from the third land 38, as shown in FIG. 2B.The second land 36 may be flat as shown in FIG. 2A, or tapered inwardlywith increasing distance from the third land 38, as shown in FIG. 2C.The third land 38 is preferably flat in all cases but with a sealstructure to be discussed subsequently. The tapers in the first land andsecond land, where present, aid in guiding the pipe 24 into its properlyseated position.

A circumferentially extending first recess 42 lies between the firstland 34 and the second land 36. A circumferentially extending secondrecess 44 lies between the second land 36 and the third land 38. In theillustrated preferred embodiment the recesses 42 and 44 are eachdepicted as a flat-bottomed annulus lying between the local portion ofthe internal surface 32 and the pipe 24 when the pipe is inserted intothe coupling 22. Other shapes of the recesses are also operable.

Preferably, a first circumferential seal 46 is present on the first land34 and a second circumferential seal 48 is present on the third land 38.The seal 46 retains a pressure in the first recess 42 and prevents anyfluid cement present in the first recess 42 from leaking past the stop40 and into the interior of the pipe 24. The seal 48 retains a pressurein the second recess 44 and prevents any fluid cement present in thesecond recess 44 from leaking out of the coupling 22.

A gate channel 50 extends axially through the second land 36 andcommunicates fluid pressure and fluid flow between the first recess 42and the second recess 44.

A fluid injection port 52 extends through the body 26 of the coupling 22and into the first recess 42, thereby communicating fluid pressure andfluid flow between the exterior of the coupling 22 and the first recess42. A fluid vent port 54 extends through the body 26 of the coupling 22and into the second recess 44, thereby communicating fluid pressure andfluid flow between the second recess 44 and the exterior of the coupling22. The vent port 54 is preferably of a smaller cross-sectional areathan the injection port 52, so that the vent port supports a pressurewithin the recesses 42, 44 when fluid cement is injected through theinjection port 52 into the recesses 42, 44. The ports 52 and 54 may beseen in the exterior view of FIG. 1 and in the leftmost coupling of FIG.2A, which has been drawn rotated by 90 degrees from the rightmostcoupling of FIG. 2A so as to illustrate the ports.

The ports 52, 54, on the one hand, and the gate channel 50, on theother, are located at circumferentially remote locations of the coupling22, and preferably at approximately diametrically opposite locations ofthe coupling 22, when the coupling is viewed end-on as in FIG. 3. Thetwo ports 52 and 54 are located at a port circumferential location andthe gate channel 50 is located at a gate channel circumferentiallocation that is circumferentially spaced about 180° from the portcircumferential location. The circumferential spacing need not beexactly 180° , but should be such that the ports 52, 54 and the gatechannel 50 are roughly oppositely positioned for the reasons to bediscussed next.

FIG. 4 illustrates the fluid flow path when a fluid, specifically afluid plastic cement, is used to solvent weld and thence permanentlybond the pipe 24 to the coupling 22. The fluid cement is injected intothe injection port 52 using any convenient device such as a syringe or apump that seals to the external surface 30 around the injection port 52so that the fluid is directed into the injection port 52 under pressure.The fluid cement enters the first annular recess 42 and flowscircumferentially through the recess 42 toward the circumferentiallyopposite side of the coupling 22. The fluid cement flows in bothcircumferential directions from the injection port 52, as indicated bythe flow lines 56, to completely fill the first annular recess 42. Uponreaching the region of the first recess 42 that is circumferentiallyopposite to the injection port 52, the fluid cement flows through thegate channel 50, as indicated by the flow line 58. The fluid cement thenenters the second annular recess 44 and flows circumferentially throughthe recess 44 toward the opposite side of the coupling 22 and thence tothe fluid vent port 54. The fluid cement flows in both circumferentialdirections from the gate channel 50, as indicated by the flow lines 60,filling the second annular recess 44. The complete filling of therecesses 42 and 44 is important for mechanical strength of the joint andalso to prevent leakage through the joint when the coupling is inservice.

Tests using prototype couplings 22 fashioned from a transparent materialand a dyed fluid cement have verified the fluid flow paths described inthe preceding paragraph. The reduced cross-sectional area of the fluidvent port 54 aids in maintaining a positive pressure of fluid cementwithin the recesses 42, 44 during this filling operation, ensuring thatthe recesses are fully filled with the cement. The circumferential flowof fluid cement in the first recess 42 mandated by the oppositelydisposed injection port 52 and gate channel 50 and the circumferentialflow of fluid cement in the second recess 44 mandated by the oppositelydisposed gate channel 50 and vent port 54 ensures a shearing actionbetween the fluid cement on the one hand, and the surface of therecesses and the pipe on the other. The seals 46 and 48 prevent fluidcement from leaking out of the recesses 42, 44 during this cementinjection operation. When the person performing the solvent welding andbonding operation sees fluid cement begin to emerge from the vent port54, the recesses 42, 44 have been filled and no further fluid cementneed be injected. In an extension of this testing technique tocommercial service, the fittings and couplings may be made from atransparent plastic material and a colored dye may be mixed into thecement, so that the user can visually verify the success and completionof the solvent bonding operation.

The shearing action achieved by the structure of the fitting simulatesthe manual rotation of the fitting and the pipe that is used inconventional fitting systems, thereby achieving a full wetted bonding ofthe external surface of the pipe to the internal surface of the fitting,but without any manual rotation. It is therefore possible to dryassemble the piping system and then permanently solvent weld and bondthe fittings and pipes without disassembly or using relative rotationduring the solvent welding operation. The dry assembly and permanentbonding operation is therefore accomplished much faster and moreeconomically than in the conventional approach.

FIGS. 5-7 illustrate three preferred embodiments of the seals 46, 48.These embodiments are illustrated for the second seal 48, but areequally applicable to the first seal 46. In the embodiment of FIG. 5, acircumferential O-ring groove 62 is formed in the third land 38, and anelastomeric O-ring 64 is placed into the groove 62. In the embodiment ofFIG. 6, a circumferential slot 66 is molded into the third land 38, anda circumferentially extending elastomeric insert 68 is formed in theslot 66 and extending out of the slot 66. The insert 68 may, forexample, be configured in the manner of an O-ring, or it may have aflap-like wiper/seal shape as illustrated in FIG. 6 which permits thepipe to slide from right to left across the seal but acts to retain thefluid cement within the adjacent recess 44 during fluid cementinjection. In both of the embodiments of FIGS. 5 and 6, the body 26 ofthe coupling 22 is typically formed of a hard, rigid plastic materialsuch as PVC (Poly(Vinyl Chloride)), ABS(Acrylonitrile-Butadiene-Styrene), or CPVC (Chlorinated Poly(VinylChloride)). The O-ring 64 and the insert 68 are formed of anelastomeric, rubbery material that is resistant to damage by solvents.The preferred materials for the O-ring 64 and the insert 68 are thepolyolefins such as polypropylene, polyethylene, or polybutene. In theapproach of FIG. 5, the body 26 is typically injection molded, theO-ring 64 is separately formed, and the O-ring 64 is thereafter insertedinto the O-ring groove 62. In the approach of FIG. 6, the body 26 istypically injection molded in a first injection molding operation, andthe insert 68 is molded in place in a second, sequential injectionmolding operation.

Another version of the seal is illustrated in FIG. 7. Here, the seal isa thin, circumferentially extending flap 70 protruding radially inwardlyfrom the third land 38. The flap 70 is made sufficiently thin so as tobe flexible and bend so as to scrape across the surface of the pipe whenthe pipe is inserted into the coupling. The flap 70 thus forms a sealbetween the coupling and the pipe. The flap 70 is made of the same hard,rigid material as the body 26 and is co-formed with the remainder of thecoupling, preferably by injection molding. The flap 70 is, however,sufficiently thin, preferably on the order of about 0.005 inches thickin the axial direction, that it can bend somewhat to conform to thesurface of the pipe. Optional circumferential undercuts 71 on eitherside of the flap 70 also aid in achieving a required small degree offlexibility of the flap.

The seal embodiments of FIGS. 5 and 6 are tighter and less subject toleakage of the fluid cement during the solvent bonding operation thanthe seal embodiment of FIG. 7. On the other hand, the seal embodiment ofFIG. 7 is less expensive to produce than those of FIGS. 5 and 6. Thetradeoff between seal performance and cost is used to advantage when thefittings are designed for particular applications. For a home waterdrain system using relatively large-diameter piping, for example, aslight leaking of the fluid cement during the injection operation may beless important than achieving a low cost of the fittings, so the seal ofFIG. 7 is preferably used. For a laboratory piping system usingsmall-diameter piping, for example, where any leakage around the firstseal 46 may obscure a portion of the flow path through the fitting andfitting cost is less of a concern, one of the embodiments of FIGS. 5 and6 is preferably used.

FIG. 8 is a schematic cross-sectional view of a piece of pipe 24 such aspurchased commercially and with which the fitting 20 of the invention istypically used. The pipe 24 is manufactured commercially by an extrusionoperation, which is inexpensive but often leads to irregularities inwall thickness, diameter, and concentricity of the pipe. Theseirregularities are illustrated in reference to a perfect circle 72 thatis circumscribed in the pipe 24. Commercial pipe specifications permitsuch irregularities. For example, ASTM Specification D2665-94 forPoly(Vinyl Chloride) drain, waste, and vent pipe with a nominal 2 inchinside diameter permits an outside diameter of 2.375±0.006 inches with apermissible deviation of the diameter (i.e., out of roundness) of ±0.012inches. ASTM Specification D2661-94a for Acrylonitrile-Butadiene-StyreneSchedule 40 pipe with a nominal 2 inch inside diameter permits anoutside diameter of 2.375+0.010/-0.000 inches with a permissibledeviation of the diameter (i.e., out of roundness) of 0.024 inches.

The fitting 20 and coupling 22 of the invention are designed toaccommodate these irregularities in commercially available pipe withoutloss of function. In the absence of the three lands 34, 36, and 38, thepipe 24 would fit within the coupling 22 on an irregular, off-centermanner. This positioning of the pipe within the coupling, and consequentirregularity in the thicknesses of the annular region(s), would causethe fluid cement to flow in an irregular manner so that fullcircumferential coverage and thence a strong mechanical bonding and goodsealing of the pipe to the coupling would be problematical. Once thepipe is rested upon the lands so that the sizes of the recesses 42, 44are well established, the seals 46 and 48 serve to achieve sealing ofthe fluid cement during the injection operation, regardless ofirregularities in the external shape of the pipe 24. The lands and sealsthus cooperate so that the lands may be made sufficiently oversize indiameter to receive pipe that is within the maximum limits of thecommercial specifications, with the seals extending sufficiently farinwardly to accommodate the irregularities in the external surface ofthe pipe permitted by the commercial specifications. Previously knowndesigns of injection fittings did not have such a configuration and itsassociated benefits.

The fitting 20 and coupling 22 of the invention may be made in any sizeand configuration that may be required for a specific application, andFIG. 9 illustrates some of the alternatives. In FIG. 9, the fitting 80is a straight fitting with couplings at the opposite ends, as has beendiscussed in relation to FIG. 2A. The fitting 82 is an elbow fitting(which could be a 90° fitting or of any other desired angle) with afirst coupling 84 being for a pipe 24 having a first diameter and asecond coupling 86 being for a pipe 24' having a second diameter. Thefitting 88 is a T-fitting having three couplings, the linear fittingsbeing used with the pipe 24 having the first diameter and the fitting at90° being used with the pipe 24' having the second diameter. The fitting90 also illustrates that the positions of the injection port 52 and thevent port 54 may be reversed as between communication with the first andsecond recesses. The fitting 90 is an integral fitting co-formed withthe pipe 24" at its end. An integral fitting may also be formed on otherarticles such as valves or other types of hardware. Such integralfittings would typically be injection molded integrally with thehardware to which they are attached.

The preferred embodiment of the present invention is found in fittingsused with generally cylindrical piping as discussed in relation to FIGS.1-9, but the invention is not so limited. The sealing approach may beused in any other suitable application, with an example shown in FIG.10. A base 100 of a box 102 whose lid 104 is to be hermetically sealedin place is provided with a coupling 106 like that discussed previously,except that the coupling is not cylindrical but has the desired shape ofthe rim of the lid 104, in this case a rectangle. The internal structureof the coupling 106 follows the same principles as those discussedpreviously.

FIG. 11 illustrates the preferred practice of the present invention. Thepipe and fittings discussed previously are provided, numeral 110, anddry fitted together, numeral 112. By "dry fitting" is meant that theparts are fitted together with no cement present, so that the sizes andlengths can be adjusted as necessary to achieve the desired system.After dry fitting is complete, fluid cement is injected into the fluidinjection ports 52 in a sequential manner, one fitting after the next,numeral 114. The cement is allowed to harden, completing the permanentassembly of the piping system. No disassembly is performed between steps112 and 114 to coat the parts with cement.

Although a particular embodiment of the invention has been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

What is claimed is:
 1. A connector structure to be used with a pipe of apipe nominal diameter, comprising a hollow body having an externalsurface and including at least a first coupling, the first couplingincludinga first cylindrical internal land; a second cylindricalinternal land; a third cylindrical internal land, wherein the firstcylindrical internal land, the second cylindrical internal land, and thethird cylindrical internal land are collinear and of a diametersufficiently larger than the pipe nominal diameter to permit the pipe tobe slipped into the hollow body to rest upon the lands; acircumferential seal located at one of the first cylindrical internalland and the third cylindrical internal land; a circumferentiallyextending internal first recess lying between the first cylindricalinternal land and the second cylindrical internal land; acircumferentially extending internal second recess lying between thesecond cylindrical internal land and the third cylindrical internalland; a gate channel through the second cylindrical internal landcommunicating between the first recess and the second recess at a gatechannel circumferential location; an injection port communicatingbetween the first recess and the external surface at a portcircumferential location, the port circumferential location beingdisplaced by about 180 degrees around the circumference of the body fromthe gate channel circumferential location; and a vent port communicatingbetween the second recess and the external surface at about the portcircumferential location.
 2. The connector structure of claim 1, whereinthe circumferential seal comprisesa circumferential groove in thecylindrical internal land, and an O-ring lying in the circumferentialgroove.
 3. The connector structure of claim 1, wherein the body isformed of a relatively rigid material, and wherein the circumferentialseal comprisesa circumferential ring of a relatively compliant materialintegral with the relatively rigid material of the body.
 4. Theconnector structure of claim 1, wherein the body is formed of arelatively rigid material and wherein the circumferential sealcomprisesa circumferential flap of the relatively rigid material.
 5. Theconnector structure of claim 1, wherein the circumferential sealcomprisesa first circumferential seal at the first cylindrical internalland, and a second circumferential seal at the third cylindricalinternal land.
 6. The connector structure of claim 1, wherein the bodyfurther includesa second coupling having the same structure as the firstcoupling.
 7. The connector structure of claim 6, wherein the bodyfurther includesa third coupling having the same structure as the firstcoupling.
 8. The connector structure of claim 1, wherein the body ismade of a plastic.
 9. The connector structure of claim 1, wherein thebody is made of a plastic selected from the group consisting ofpoly(vinyl chloride), acrylonitrile-butadiene-styrene, and chlorinatedpoly(vinyl chloride).
 10. The connector structure of claim 1, whereinthe vent port has a smaller cross sectional area that the injectionport.
 11. The connector structure of claim 1, further includinga pipereceived within the coupling and resting upon the first cylindricalinternal, the second cylindrical internal land, and the thirdcylindrical internal land.
 12. The connector structure of claim 11,further includinga mass of cement lying within the first recess, thesecond recess, and the gate channel.
 13. The connector structure ofclaim 12, wherein the cement substantially fills the first recess, thesecond recess, and the gate channel.
 14. The connector structure ofclaim 1, wherein the coupling is, at least in part, transparent.
 15. Theconnector structure of claim 1, wherein at least one of the first landand the second land is tapered inwardly with increasing distance fromthe third land.
 16. A connector structure to be used with a pipe of apipe nominal diameter, comprising a hollow body having an externalsurface and including at least a first coupling, the first couplingincludinga first cylindrical internal land; a stop extending radiallyinwardly from the first cylindrical internal land; a second cylindricalinternal land; a third cylindrical internal land, wherein the firstcylindrical land, the second cylindrical land, and the third cylindricalinternal land are collinear and of a diameter sufficiently larger thanthe pipe nominal diameter to permit the pipe to be slipped into thehollow body to rest upon the lands; a circumferentially extendinginternal first recess lying between the first cylindrical internal landand the second cylindrical internal land; a circumferentially extendinginternal second recess lying between the second cylindrical internalland and the third cylindrical internal land; a gate channel through thesecond cylindrical internal land communicating between the first recessand the second recess at a gate channel circumferential location; aninjection port communicating between the first recess and the externalsurface at a port circumferential location, the port circumferentiallocation being displaced by about 180 degrees around the circumferenceof the body from the gate channel circumferential location; and a ventport communicating between the second recess and the external surface atabout the port circumferential location.
 17. The connector structure ofclaim 16, wherein at least one of the first land and the second land istapered inwardly with increasing distance from the third land.
 18. Theconnector structure of claim 16, further includinga circumferential seallocated at one of the first internal cylindrical land and the thirdinternal cylindrical land.
 19. The connector structure of claim 16,wherein the circumferential seal comprisesa first circumferential sealat the first internal cylindrical land, and a second circumferentialseal at the third internal cylindrical land.
 20. A connector structure,comprising a hollow body having an external surface and including atleast a first coupling, the first coupling includinga first internalland; a second internal land; a third internal land, wherein the firstland, second land, and third land are collinear and congruent; acircumferentially extending internal first recess lying between thefirst land and the second land; a circumferentially extending internalsecond recess lying between the second land and the third land; a gatechannel through the second land communicating between the first recessand the second recess at a gate channel circumferential location; afirst seal extending around the first internal land; a second sealextending around the third internal land; an injection portcommunicating between the first recess and the external surface at aport circumferential location, the port circumferential location beingdisplaced by about 180 degrees around the circumference of the body fromthe gate channel circumferential location; and a vent port communicatingbetween the second recess and the external surface at about the portcircumferential location.
 21. The connector structure of claim 20,wherein at least one of the first land and the second land is taperedinwardly with increasing distance from the third land.
 22. The connectorstructure of claim 20, wherein at least one of the first seal and thesecond seal comprisesa circumferential flap made of the same material asthe body.
 23. A connector structure, comprising a hollow body having anexternal surface and including at least a first coupling, the firstcoupling includinga first internal land; a second internal land; a thirdinternal land, wherein the first land, second land, and third land arecollinear and congruent; a circumferentially extending internal firstrecess lying between the first land and the second land; acircumferentially extending internal second recess lying between thesecond land and the third land; a circumferential seal located at one ofthe first internal land and the third internal land; a gate channelthrough the second land communicating between the first recess and thesecond recess at a gate channel circumferential location; an injectionport communicating between the first recess and the external surface ata port circumferential location, the port circumferential location beingcircumferentially remote from the gate channel circumferential location;and a vent port communicating between the second recess and the externalsurface at about the port circumferential location.
 24. The connectorstructure of claim 23, wherein the hollow body is cylindrical.
 25. Theconnector structure of claim 23, wherein the hollow body is notcylindrical.
 26. The connector structure of claim 23, wherein at leastone of the first land and the second land is tapered inwardly withincreasing distance from the third land.
 27. The connector structure ofclaim 23, wherein the circumferential seal comprises.a circumferentialflap made of the same material as the body.